Best technique for Bubble Nebula

[Grandad]

I started collecting subs of NGC7635 the other night (only about 90 minutes before the mist rolled in). My plan was to collect a couple of hours of Lights, 45 minutes each of 2x2 binned rgb and then add perhaps a hour of binned HA to the red channel. Would this work or should I be spending more time on the HA?

Any advice welcomed

Thanks

[ollypenrice]

I would never bin Ha. I tried once but it looked awful. The stars were extremely 'blocky' and at your short FL in the 72 I think they'd be worse than mine were at a metre of FL.

Ha holds all the detail, particularly in this object. All those little hints of structure inside the bubble itself... You need resolution and the Ha has nearly all of it.

I rarely bin colour at all and never if I'm aiming to add Ha because of the star size mismatch (Ha stars are nice and tiny).

This was without any binning, HaLRGB, the Ha added to red in blend mode lighten and lightly as luminance at the end. (15%)

http://ollypenrice.smugmug.com/Other/Nebulae-and-clusters/i-RGkB2cG/0/X3/BUBBLE-HaLRGBcleaned-X3.jpg

Olly

[Grandad]

Thanks Olly

I suspected I was going down the wrong route.

What would be a minimum exposure per frame for unbinned ha?

John

[ollypenrice]

Ha is slow as in slow so go for as long as your guider will hold up, I'd say. People who can do it often go to 30 minutes in Ha. I go for 15 or 20 because I don't have the darks for longer and they take so much time to do and to update! Your polar alignment needs to be good too, by the way, for long subs. Watch the corner stars for signs of rotation.

Olly

[Grandad]

Thanks again.

Great picture. Gives me something to aspire to.